In describing material from cocoons gathered from the wild in Mexico, one researcher used the term "silk" to describe such fiber:
The cultivation of
nopals (Nopalea cochenillifera) for raising cochineal and the keeping of
stingless bees are practices now virtually abandoned. Wild silk used to be
gathered by Zapotec women and woven into fabric which was sold with high
profits. (Matthew Wallrath, "Excavations in the Tehuantepec Region, Mexico,"
Transactions of the American Philosophical Society, New Series—Volume 57,
Part 2, 1967, p. 12, emphasis added)